Protests on Nauru in March, in which asylum seekers and refugees called for an end to offshore processing. A television crew has been granted access to the detention centre for the first time.

A news crew from Channel Nine’s A Current Affair has been given rare access to Nauru and the Australian offshore immigration detention centre.

The tabloid TV show has billed its report as an exclusive look at “how asylum seekers and refugees are really living” but advocates and lawyers have raised concerns about its freedom and access on the island.

A teaser commercial for Monday’s show says the story will “stun Australia”, and claims to have already sent refugee advocates “into a frenzy”.

It includes a short clip of an unidentified man saying “fuck Australia”, and shows the inside of cramped, shared accommodation areas, and the protests which have been occurring daily for almost three months.

It also claims it had full access although people on the island have said the crew appeared to have Nauruan officials or police escorting them to particular places.

The arrival of the news crew has prompted concern among detainees, some whom have accused the group of filming them without permission.

Some advocates had warned refugees against speaking to the journalists.

Nauru is notoriously media averse, and this marks the first time a TV news crew has been allowed on the island to film the centre. The government charges media a non-refundable $8,000 visa application fee. Since the centre opened only one journalist has legally reported from the island.

The Australian’s Chris Kenny speculated at the time of his reports that his support for “strong border protection policies” had perhaps helped.

The Weekly Beast: sifting truth from spin in Chris Kenny’s trip to Nauru

The human rights lawyer George Newhouse said he was concerned about the conditions under which the news team were granted visas, and that “they may not be seeing the harsh realities of the existence of many of the asylum seekers and refugees.”

Newhouse told Guardian Australia he’d heard reports the film crew had visited the new hospital, which was not yet operating, and noted it was only last month that a man died “in disturbing circumstances” at the Nauru hospital.

“There are some offices that are being used for consultations but it’s not operating as a hospital. What they’re seeing is a papier mâché front,” he said.

“It’s important to note it’s taken four years for Nauru to be in a state where journalists can actually be shown some of what’s going on.”

He said it was not just journalists who were denied access, but also lawyers.

“I have clients who have been raped on that island and we can’t even get copies of their police statements,” he said.

“I’m acting for the family of a man who died on the island and I can’t get access to the island or their court system. It’s a black site in the Pacific and one needs to question the basis on which particular journalists are being granted access to it.”

On Wednesday, before the revelation that A Current Affair was on the island, the government of Nauru’s information office tweeted there had been no change to the visa process.

“Entry into Nauru is at sole discretion of Nauru government and standard application procedures apply,” it said.

The Greens senator Sarah Hanson-Young said the visit seemed like “ a cynical political move on the eve of the election”.

“The government has banned me from visiting all of Australia’s detention centres during the caretaker period of government, but it seems this tabloid TV show has been given an all access pass,” she told Guardian Australia.

“When I visit detention centres, including the one on Nauru, I’m told that the managers madly rush around cleaning things up and trying hide the worst of the neglect before I arrive. I have no doubt that the same thing would have happened before this film crew were allowed into the camp and I’m worried the Australian people won’t see the reality of life inside these camps.”

A spokeswoman for the department of immigration said it was aware of the visit, but access was a matter for the government of Nauru. She said the Australian government did not facilitate A Current Affair’s visit.

The Australian government has defended its media blackout inside detention centres. The Coalition’s campaign spokesman, Mathias Cormann, this week said preventing access was part of “operational discipline” and suggested it prevented sharing intelligence information with people smugglers. He declined to give further explanation.